This invention relates to gas turbine engines, and more particularly to a seal member extending between an array of stator vanes and the inner case of such an engine.
A gas turbine engine has a compression section, a combustion section, and a turbine section. The turbine section includes a rotor assembly and a stator assembly. One or more rows of rotor blades extend outwardly on the rotor assembly. The stator assembly includes an outer case and an inner case. One or more rows of stator vanes extend between the outer case and the inner case. An annular flow path for working medium gases extends through the alternating rows of vanes and blades. Working medium gases are pressurized in the compression section, burned with fuel in the combustion section and expanded in the turbine section. The temperature of the working medium gases discharging from the combustion section into the turbine often exceed fourteen hundred degrees Celsius (1400.degree. C.).
The hot gases entering the turbine section lose heat to the stator vanes and the inner case causing thermal growth of the vanes and the inner case. These vanes are cooled to prevent a deterioration in physical properties and to ensure an adequate life. The performance of the engine is diminished by the loss of cooling air through leak paths between the vanes and the inner case. Typical constructions using high pressure air as the cooling medium are shown in U.S. Pat. Nos. 3,957,393 to Bandurick entitled "Turbine Disk and Sideplate Construction"; 3,980,411 to Crow entitled "Aerodynamic Seal for a Rotary Machine"; and 4,025,226 to Hovare entitled "Air Cooled Turbine Vane".
As the working medium gases expand through the turbine vanes, the working medium gases exert nonuniform aerodynamic forces on the vanes. These forces are a primary cause of vane vibration. The vibration and the forces can create high stresses in the vanes which ultimately may cause fatigue failure. Accordingly, scientists and engineers are continuing to search for seal structures having good sealing effectiveness between the vanes and the inner case, and an ability to damp vane vibration.